Modular rough terrain vehicle

ABSTRACT

A rough terrain vehicle including an elongated main frame for supporting a self-contained v-haul body; first and second forwardly-extending frame arms located on opposite sides of the main frame; third and fourth rearwardly-extending frame arms located on opposite sides of the main frame, each arm having a wheel mounted thereon. Also included are first and second cross members pivotably connected to the arms configured to enable the main frame and the frame arms to pivot about a lengthwise axis of the main frame. First and second length-adjustable member operatively connected to the first frame arm and the third frame arm and the second frame arm and the fourth frame arm, respectively; selective movement of each length-adjustable member causing the associated arm to move up or down; and a level detector for producing and applying leveling signals to each of the length-adjustable members to maintain the elongated main frame in a relatively level orientation when the vehicle encounters uneven terrain.

BACKGROUND OF THE INVENTION

This invention relates generally to an automatic leveling vehicle usedto keep the vehicle's operator level when traveling on uneven terrain,and more particularly, to an all terrain vehicle which supports andmaintains an operator portion of the vehicle body in a relatively levelposition even when the vehicle is traveling along a slanted grade oruneven terrain.

Many vehicles have been designed to operate off of improved roadways andover uneven terrain. Such vehicles typically include a rigid, parallelframe and a fixed wheelbase. When such a vehicle travels along a slantedgrade or uneven terrain, the wheels on one side of the vehicle are lowerthan the wheels on the other side of the vehicle, so the vehicle bodynecessarily adopts a tilted orientation roughly equal to the slantedgrade of the ground. The tilted orientation of the vehicle body can bequite uncomfortable and can cause fatigue for the driver and passengers,particularly when the grade is steep. There is also a danger the vehiclewill roll over.

SUMMARY OF THE INVENTION

Embodiments of the present invention are directed to a rough terrainvehicle including an elongated main frame for supporting a body; firstand second forwardly-extending frame arms located on opposite sides ofthe main frame, each of which includes a proximal end and a distal end,each proximal end being pivotably connected to the main frame, and eachthe distal end having at least one rotatable wheel mounted to each arm;third and fourth rearwardly-extending frame arms located on oppositesides of the main frame, each of which includes a proximal end and adistal end, each the distal end having at least one rotatable wheelmounted to each arm; a first generally U-shaped cross member pivotablyconnected to the first and second frame arms and supporting a forwardend of the main frame; a second generally U-shaped cross-memberpivotably connected to the third and fourth frame arms and supporting arearward end of the main frame; the cross members being configured toenable the main frame and the frame arms to pivot about a lengthwiseaxis of the main frame for the purpose of maintaining the main framelevel from side to side. Also included is a first length-adjustablemember operatively connected to the third frame arm and the first framearm; selective movement of the first length-adjustable member causingthe distal end of the first frame arm to move up or down; a secondlength-adjustable member operatively connected to the fourth frame armand the second frame arm; selective movement of the secondlength-adjustable member causing the distal end of the second frame armto move up or down; and a level detector for producing and applyingleveling signals to each of the length-adjustable members; the levelingsignals causing each of the length-adjustable members to position eachthe first and second frame arms such that the elongated main frame ismaintained in a relatively level orientation when the vehicle encountersuneven terrain.

Also included is a trailer for traveling over rough terrain and attachedto a vehicle that includes a motor for pulling the trailer, the trailerincluding an elongated main frame for supporting a trailer body; aplurality of rearwardly-extending frame arms located on opposite sidesof the main frame, each of which includes a proximal end and a distalend; each proximal end being pivotably connected to the main frame andeach distal end having at least one rotatable wheel mounted thereon; agenerally U-shaped cross member associated with the plurality of framearms for supporting the main frame, the cross-member being pivotablyconnected to the plurality of frame arms and being configured to enablethe main frame and the plurality of frame arms to pivot about alengthwise axis of the main frame for the purpose of maintaining themain frame level from side to side; a pivot axle associated with theplurality of frame arms for connecting the proximal ends of each theplurality of frame arms, the pivot axle permitting relative movement ofthe plurality of frame arms about the pivot axle; at least onelength-adjustable member operatively connected to the main frame and atleast one of the plurality of frame arms; selective movement of thelength-adjustable member causing the distal end of at least one of theplurality of frame arms to move up or down; a level detector forproducing and applying leveling signals to each of the length-adjustablemembers; the leveling signals causing each of the length-adjustablemembers to position each the first and second frame arms such that theelongated main frame is maintained in a relatively level orientationwhen the vehicle encounters uneven terrain.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front perspective view of the present modular rough terrainvehicle on uneven terrain;

FIG. 2 is a top perspective view of the present modular rough terrainvehicle on even terrain with portions omitted for clarity;

FIG. 3 is a top view of the present modular rough terrain vehicle withportions omitted for clarity;

FIG. 4 is a bottom view of the present modular rough terrain vehiclewith portions omitted for clarity;

FIG. 5 is an exploded, somewhat schematic, perspective view of thepresent modular rough terrain vehicle with portions omitted for clarity;

FIG. 6 is a side perspective view of the suspension system of thepresent modular rough terrain vehicle with portions omitted for clarity;

FIG. 7A is a side perspective view of the cross-member mounting assemblyof the present modular rough terrain vehicle with portions omitted forclarity;

FIG. 7B is a front view of the tab inserted in the opening of the frameextension plate with the tab at a neutral position;

FIG. 7C is a front view of the tab inserted in the opening of the frameextension plate with the tab at a rotated position;

FIG. 8 is a top plan view of the hydraulic control system of the presentinvention; and

FIG. 9 is a perspective view of an automatic leveling detector for thisinvention.

FIG. 10 is a top perspective view of a trailer for traveling over roughterrain with portions omitted for clarity;

FIG. 11 is an elevated view of a length adjustable member of the vehicleof FIG. 1 connected to an air spring; and

FIG. 12 is a top view of a drive train system used in the vehicle ofFIG. 1.

DETAILED DESCRIPTION OF THE EMBODIMENTS

One embodiment of a modular rough terrain vehicle is shown in FIG. 1 andis generally designated 10 and includes a frame generally designated as12 for supporting a body 14 with at least one operator seat 16 allowingan operator to ride on the vehicle as it travels. This embodimentgenerally illustrates how the body 14 is maintained in a generally levelorientation even though the vehicle traveling on a substantial incline.While this embodiment has four wheels 18, the preferred embodiment shownin FIGS. 2-7 is intended to depict a larger vehicle that has tandem rearwheels 18. The larger vehicle embodiment is not shown with the body forthe sake of clarity, since the frame and structural features are moreimportant to an understanding of the vehicle. It should also beappreciated that the same concepts explained below for the vehicle 10are also applicable to a trailer being pulled by the vehicle which isshown in FIG. 11.

As shown in FIGS. 2-3, the larger vehicle embodiment, indicated at 20,includes an elongated main frame 22 for supporting a body or a unifiedframe body with a V-shaped hull design (not shown). Attached to the mainframe 22 are first and second forwardly-extending frame arms 24, 26.Each forwardly-extending frame arm 24, 26 includes a proximal endpivotably connected to the main frame 22 and a distal end having atleast one rotatable wheel 18 mounted thereon. Also attached to the bodyare third and fourth rearwardly-extending frame arms 32, 34. Eachrearwardly-extending frame arm 32, 34 also includes a proximal endpivotably connected to the main frame 22 and a distal end having atleast one rotatable wheel 18 mounted thereon. It is preferred that theproximal ends of the first and third arms 24, 32 be adjacent to eachother. Similarly, it is also preferred that the proximal ends of thesecond and fourth arms 26, 34 also be adjacent to each other.

In this embodiment, a first pivot axle 36 connects the proximal ends ofthe first and second frame arms 24, 26 and a second pivot axle 38connects the proximal ends of the third and fourth 32, 34 frame arms.Each of the pivot axles 36, 38 permits relative movement of the attachedframe arms 24, 26, 32, 34 about their associated pivot axle. It ispreferred that axles 36, 38 be located near the center of the vehicle 10and be positioned parallel to each other. It is also contemplated that asingle center axle 36 or 38 may be used instead of two parallel axles.As should be appreciated, the modular frame 12 design of this embodimentuses interchangeable parts that allows for efficient maintenance andrepair. In addition, this frame 20 design is also scalable to permitinstallation in vehicles 20 of various sizes.

In the preferred configuration, each frame arm 24, 26, 32, 34 furtherincludes a stabilizer arm 40 interconnecting the main frame 22 and eachframe arm for providing lateral stability of the distal end of eachframe arm. Each stabilizer arm 40 includes at least one link 42 (seeFIG. 5) and is extendable and retractable so that the main frame 22 isadjustable relative to the position of each frame arm 24, 26, 32, 34. Itis preferred that the stabilizer arm 40 include the link 42 connected bya hinge or similar device and that each stabilizer arm is sufficientlywide to provide lateral stability to the distal end of each of the framearms 24, 26, 32, 34. In addition, each stabilizer arm 40 functions tokeep its corresponding wheel 18 generally parallel to the main frame 22.

As best shown in FIGS. 2-4, first 44 and second 48 cross-members areincluded to provide stability and secure the frame arms 24, 26, 34, 36to the pivot axles 36, 38. The first cross-member 44 is pivotablyconnected to the first and second frame arms 24, 26 for supporting afrontward end 46 of the main frame 22 and a second cross-member 48 ispivotably connected to the third and fourth frame arms 32, 34 forsupporting a rearward end 50 of the main frame 22. Each cross-member 44,48 is generally U-shaped. However, other shapes are contemplated basedon the application.

Referring now to FIGS. 4-6, both the forward 46 end and reward end 50include a suspension system 52 mounted between the main frame 22 and thecross-members 44, 48. The suspension system 52 further stabilizes thevehicle 20 when traveling on uneven terrain by allowing verticalmovement of the main frame 22 and attached body (not shown). While aparticular suspension system 52 is set forth below, it is to beunderstood that other suspension systems 52 and configurations as knownin the art are appropriate.

In this particular embodiment, the forward end 46 and rearward end 52 ofthe main frame 22 each include a cavity 56 where the suspension system52 is mounted. Each suspension system 52 includes a suspension plate 58which is affixed to a cavity ceiling 60 and extends generally along thelength of the cavity 56. It is preferred that the plate 58 be elongatedand triangular in shape. However, other shapes for the plate 58, such asrectangular, are contemplated. The plate 58 includes a fixed end 62 anda free end 64 located opposite to the fixed end. The fixed end 62 ispreferably mounted to the portion of the cavity ceiling 60 locatedfurthest from each respective pivot axle 36, 38 using a hinge thatpermits movement of the free end 64. Other suitable mounting mechanismsare contemplated for connecting the fixed end 62 to the cavity ceiling60. The free end 64 includes an aperture 66 configured for receivablyengaging a vertical rod 68 mounted to the cavity ceiling 60. Theaperture 66 is sized to limit horizontal movement of the free end 64while permitting vertical movement of the free end along the rod 68. Inaddition, the preferred configuration includes a stopper 70 to limit themagnitude of free end 64 vertical movement to the length of the rod 68.Alternatively, the free end 64 may be a hinge as shown in FIG. 5.

In addition, the plate 58 is connected to the cross member 44, 48,preferably using a rotary ball hitch 71 or similar device. Thesuspension system 52, 54 in this embodiment also includes a spring 72positioned between the middle of the plate 58 and cavity ceiling 60.Other compressible and retractable devices such as inflatable flexiblemembers or air bags may be used instead of the spring 72. The spring 72or airbag helps absorb impact and provide comfort for the operator whenthe vehicle 20 encounters uneven terrain.

As illustrated in FIGS. 2, 3 and 7A, each cross-member 44, 48 connectsto the corresponding frame arms 24, 26, 32, 34 using a cross-membermounting assembly 73 that includes a connection bracket 74 and a weighttransfer arm 75. It is also contemplated that the cross-member mountingassembly 73 include a spring or air bag (not shown) connected to thecross-member 44, 48 and connection bracket 74 to provide additionalstability. The connection bracket 74 is mounted to each frame arm 24,26, 32, 34 using a pin 76 (FIG. 7A) or other suitable connectiondevices. The pin 76 allows for lateral movement of the mounting assembly73 relative to the frame arm 24, 26, 32, 34. Further, the connectionbracket 74 is preferably mounted to the frame arm 24, 26, 32, 34 at aposition generally perpendicular to each cross-member 44, 48.

The weight transfer arm 75 is pivotably attached to each connectionbracket 74 using a hinge or similar device. The opposite end of theweight transfer arm 75 is then attached to the correspondingcross-member 44, 48 using a ball joint (shown in FIG. 2), clevisconnection (shown in FIG. 5.) or similar connection mechanism. As such,the ability of the weight transfer arm 75 to pivot permits side to sidemovement of the connected cross-member 44, 48 when uneven terrain isencountered. In addition, the mounting assembly 73 links the main frame22 with each frame arm 24, 26, 32, 34 via the cross-members 44, 48 sothat the frame arms are in synchronization and appropriately adjust whenuneven terrain is traveled.

In a multiple wheel configuration, such as the six wheel 18configuration shown in FIGS. 2-4, a tandem arm 78 is connected to thedistal end of the corresponding frame arm 32, 34 for supportingadditional wheels 18. In the six wheel 18 configuration, the tandem arm78 is generally v-shaped and includes two wheels 18 rotatably mounted ateach end. Further, the tandem arm 78 is pivotably affixed to the framearm 32, 34 using an axle or other suitable device that permits relativemovement of the attached frame arms 32, 34 about the axle. In thisembodiment, the axle is of sufficient length to extend through thetandem arm 78 so that an axle cap 79 (see FIGS. 2 and 6) can be securedonto the end of the axle. However, it is also contemplated that the axleterminate so that it is flush with the tandem arm surface 80.

Referring now to FIGS. 5 and 7A, in the multi-wheel 18 configuration,each connection bracket 74 is mounted to the tandem arm 78 instead ofthe frame arm 32, 34. Similar to the four wheel configuration describedabove, the bottom portion of the connection bracket 74 is mounted to thetandem arm 78 using a pin 76 or other suitable device that permitsmovement of the mounting assembly 73 relative to the tandem arm. Alsosimilar to the four wheel 18 vehicle 20 configuration, the correspondingcross-member 44, 48 connects to the weight transfer arm 75.

However, the top portion of the connection bracket 74 further includes atab 81 that engages a frame extension 82 secured to the frame arm 32,34. The tab 81 connects to the frame extension 82 through an opening 83.Since the tab 81 is affixed to the frame arm 32, 34 through the frameextension 82, it is able to move vertically in the opening 83 when thevehicle 20 traverses uneven terrain. This maintains the connectionbracket 74 in a generally centered position relative to the cross-member44, 48. Accordingly, the width of the tab 81 should be less than thewidth of the opening 83 to permit such vertical movement. As best shownin FIGS. 7B and 7C, in this configuration, the opening 83 also includestwo half round inserts 84 that permit angular movement of the tab 81. Inoperation, the half rounds 84 rotate in its holder and allow the tab 81to move forwardly and rearwardly in addition to the vertical movementdescribed previously. This feature is best shown in FIGS. 7B and 7C. Theamount of horizontally movement permitted by the tab 81 can becontrolled by adjusting the width of the tab and half rounds 84. The tab81 is secured by a locking plate 89 (FIG. 7A) affixed to the front ofthe frame extension 82.

Additionally, as shown in FIG. 7A, in the six wheel vehicle 20configuration where an axle cap 79 (shown in FIG. 2) is present, theconnection bracket 74 includes an aperture 85 in the upper portion ofthe bracket. The aperture 85 is preferably elliptical and sized forreceiving the axle cap 79. Furthermore, the aperture 85 should be ofsufficient size to allow lateral movement of the axle cap 79 when eitherof the wheels attached to the tandem arm 78 encounters uneven terrain.As such, the aperture 85 functions to maintain equal weight on eachwheel 18 mounted to the tandem arm 78 when the wheels attached to thetandem arm encounter uneven terrain.

Finally, in the six wheel vehicle 20 configuration, the stabilizer arm40 associated with the frame arm 32, 34 attached to the tandem arm 78connects to the main frame 22 and the tandem arm 78 instead of the framearm. While a six wheel vehicle 20 configuration is explained above, itshould be appreciated that an eight wheel or additional configurationsare contemplated using the same techniques.

Referring now to FIGS. 2-4, the vehicle 20 includes a first and secondlength-adjustable member 86, 87, each respectively connected to the mainframe 22 and the first frame arm 24 and second frame arm 26. In analternate configuration, instead of attaching to the main frame 22, thefirst length-adjustable member 86 attaches to the third frame arm 32 andthe second length-adjustable member 87 attaches to the fourth frame arm34. The length-adjustable member 86, 87 connected to the main frame 22may include an air spring 77 (FIG. 11) or similar shock absorbing deviceto provide additional stability and shock absorption. In thisconfiguration, one end of the length adjustable member 86, 87 isattached to a first fixed post 91 and the opposite end is attached to apivot post 93 positioned on the main frame 22 or the third or fourthframe arm 32, 34. An airbag or air spring 77 is then connected to thepivot post and a second fixed post 95 positioned at the opposite end ofair spring 77. Movement of the pivot post 93 compresses and releases theairbag or spring 77 to absorb rough terrain shocks and maintains body 14control while the vehicle 10 travels over rough terrain. In operation,selective movement of the first length-adjustable member 86 causes thedistal end of the first frame arm 24 to move up or down. Similarly,selective movement of the second length-adjustable member 87 causes thedistal end of the second frame arm 26 to move up or down. As such, thelength-adjustable members 86, 87 work together to adjust the position ofeach frame arm 24, 26, 32, 34 and keep the main frame 22 level whenuneven terrain is encountered.

In the illustrated embodiment, the length-adjustable member 86, 87comprises a hydraulic cylinder 88 having an extendable and retractablepiston rod 90. While the attachment of the cylinder 88 is not shown inany detail, its manner of attachment is well known to those of ordinaryskill in the art. It should also be understood that otherlength-adjustable members 86, 87 commonly used in the art arecontemplated. In addition, each length adjustable member 86, 87 mayinclude a lock (not shown) to prevent movement of the length adjustablemember. Such a feature facilitates high speed movement of the vehicle 20on level terrain. Alternatively, the lock may also be used to maintainthe vehicle 10 in a level position when parked.

As best shown in FIG. 8, a control device 92 is operatively associatedwith the length-adjustable members 86, 87 for adjusting the relativepositions of the first and second frame arms 24, 26 about a neutralbaseline. The control device 92 adjusts the position of the rod 90 inthe cylinder 88 so that an extension or retraction of thelength-adjustable member 86, 87 respectively causes the frame arms 24and 26 to move above or below a neutral wheelbase line. In thisembodiment, the control device 92 is in the form of a hydraulic systemthat includes a hydraulic pump 94, a control valve 96 and hydraulichoses 98. The setup of such control devices 92 are commonly known inthat art.

The valve 96 is operable to selectively adjust the pressure of thehydraulic fluid in either the front or rear of the cylinder 88 whicheither extends or retracts the rod 90 relative to the cylinder 88. Invarious embodiments, the control valve 96 may be operated by the driveror may include a device for automatically controlling the pump 94. Inone embodiment, the control valve 96 may include a lever 100 for manualoperation to adjust the position of the rod 90 enabling the operator toselectively raise or lower either side of the vehicle 20 to conform to aparticular terrain.

Instead of operating the control device 92 manually, the control valve96 may be connected to an automatic leveling system 102 forautomatically adjusting the relative height of the first and secondframe arms 24 and 26 and leveling the vehicle 20. Preferably, theautomatic leveling system is positioned in the center of the vehicle 20near the operator 17. In an embodiment shown in FIG. 9, the automaticleveling system 102 includes a generally inverted, U-shaped pendulumsupport bar 104 which may also serve as a roll bar for the vehicle 20. Apendulum 106 has its upper end connected to a top portion 108 of thesupport bar 104 by a pivot pin 110, which allows it to pivot in thelateral direction. The lower end of the pendulum 106 preferably includesa weight 112 for providing inertia to the pendulum 106 so that it doesnot move or change directions of movement quickly. In addition, adampening structure in the form of air or hydraulic shock absorbers 114extend from the support bar 104 and are connected to the pendulum 106for dampening movement of the pendulum in the lateral direction. The bar104 has legs 116 which are provided with a pair of stops 118 forlimiting lateral movement of pendulum 106.

A translation member 120 is operatively connected to pendulum 106 fortranslating lateral movement of the pendulum into corresponding actionsof the control valve 96 to level the vehicle. In the embodiment shown inFIG. 9, the translation member 120 takes the form of a moveable pistonstructure connected to the pendulum 106 and being slidably received in acontrol box 122. As the horizontal axis of the vehicle 20 tips in eitherdirection, the pendulum 106 will correspondingly move and result in amovement of the piston structure 120 within the control box 122. Thecontrol box 122 is operatively connected to the control valve 96 by aline 124 and provides input signals to the control valve for controllingmovement of the hydraulic cylinder 88. In particular, if the pendulum106 tilts in one direction in response to the vehicle 20 traversinguneven ground, the piston 90, control box 122 and line 124 will providea signal to the control valve 96 to raise or lower the correspondingframe arm 24, 46. Thus, the vehicle 20 where the operator is located iskept at a relatively level orientation. Other automatic leveling systemsmay also be employed in the vehicle 20 of the present invention, such asusing a mercury switch which can detect if the vehicle is out of leveland send an appropriate electrical signal to the control device 92 forautomatically leveling the vehicle.

The vehicle 20 may be powered by an internal combustion, hydraulic orelectric motor 128 and includes a drive train, indicated generally at126, to power the wheels 18. Such drive train 126 systems are commonlyknown in the art with examples including a belt or a chain drive. Ahydraulic motor may also be included for rotating each wheel 18. Variousvehicle 20 configurations for the number powered wheels are contemplatedincluding 4×2 (4 wheels, 2 powered), 4×4 (4 wheels, 4 powered) and 6×4(6 wheels, 4 powered). While not shown, the body is preferably v-shapedwhen viewed from the front or rear. Such a design allows for greatermovement of the frame arms 24 26, 32, 34 in a vertical motion when thevehicle 20 is traversing uneven terrain and provides additionalstability.

Referring now to FIG. 12, the preferred embodiment includes a threeshaft drive train 126 to distribute power to the wheels 18. Power isprovided by the motor 128 through a drive shaft 129 to a differential130. The differential 130 is connected to a first left shaft 132 and afirst right shaft 134. Both the first left shaft 132 and the first rightshaft 134 each are respectively operatively associated with a secondleft shaft 136 and a second right shaft 138. Power is transferred fromthe first shafts 132, 134 to the respective second shafts 136, 138 witha chain drive 140. Power is then transferred from the second shafts 136,138 to a gear box 142, which in turn transfers power to the front wheels18. Preferably, power is transferred from the gear box 142 to the wheelusing a chain drive (not shown) located inside each of the frame arms 2426, 32, 34.

Rear wheel power is achieved though a chain drive connection 140 betweenthe second left shaft 136 and a third left shaft 144 and the secondright shaft 138 and a third right shaft 146. Similar to the front wheels18, power is transferred from the third shafts 144, 146 to a gear box142, which in turn transfers power to each rear wheel 18 via a chaindrive (not shown). In the case where the vehicle 10 includes a tandemarm 78 with multiple wheels 18 attached, power may be transferred fromthe gear box 142 to a second gear box (not shown) which transfers powerto the wheels positioned on the tandem arm.

A drive control lever (not shown) is preferably provided for engaging ordisengaging a shaft connection 148 between the third shafts 144, 146 andthe corresponding gear box 142. By engaging and disengaging the shaftconnection 148, the operator dictates whether power goes to the frontwheels 18, or both the front and rear wheels.

Additionally, a second shaft pin 150 attached to a corresponding secondshaft lever 152 (FIG. 2) is provided for connecting the second leftshaft 136 and second right shaft 138. Similarly, a third shaft pin 154attached to a corresponding third shaft lever 156 (FIG. 2) is providedfor connecting the third left shaft 144 and the third right shaft 146.As such, when the pin 150 or 154 is in a locked position, thecorresponding shaft 136 and 138 or 144 and 146 operates as a singlelocked shaft where power is distributed equally to the right and leftwheels 18. As should be appreciated, this configuration provides theoperator flexibility regarding the amount of power being distributed toeach wheel 18 relative to other wheels. Additional drive train systemsare also contemplated with one such example including using a lockingdifferential as the initial receptor of power. Such systems are known inthe art.

Operation as the vehicle 20 traverses uneven terrain will now bedescribed. When the vehicle 20 travels along the surface of a slantedgrade, the automatic level detector 102 sends a signal to the controldevice 96 indicating the direction and magnitude of adjustment requiredby each length-adjustable member 86 and 87 to keep the operator 17 in arelatively level position. The length adjustable member 86, 87 thenadjusts the position of each corresponding front frame arm 24 and 26based on the signal sent from the control device 92. Once the frontframe arms 24 and 26 adjust, the rear frame arms 32 and 34 move up anddown against the terrain to keep the frame 14 and operator at a levelposition. As such, the main frame 22 is kept in a level position. Thebody (not shown) is supported by the main frame 22, and the drivertherefore enjoys a comfortable and level driving position while thevehicle 20 travels along the slanted grade.

While various embodiments of the present invention have been shown anddescribed, it should be understood that other modifications,substitutions and alternatives are apparent to one of ordinary skill inthe art. Such modifications, substitutions and alternatives can be madewithout departing from the spirit and scope of the invention, whichshould be determined from the appended claims.

Various features of the invention are set forth in the following claims.

1. A rough terrain vehicle comprising: a body for a vehicle operator toride in; an elongated main frame for supporting said body; first andsecond forwardly-extending frame arms located on opposite sides of saidmain frame, each of which includes a proximal end and a distal end, eachsaid proximal end being pivotably connected to said main frame, and eachsaid distal end having at least one rotatable wheel mounted thereon;third and fourth rearwardly-extending frame arms located on oppositesides of said main frame, each of which includes a proximal end and adistal end, each said distal end having at least one rotatable wheelmounted thereon; a first generally U-shaped cross member pivotablyconnected to said first and second frame arms and supporting a forwardend of said main frame; a second generally U-shaped cross-memberpivotably connected to said third and fourth frame arms and supporting arearward end of said main frame; said cross members being configured toenable said main frame and said frame arms to pivot about a lengthwiseaxis of said main frame for the purpose of maintaining said main framelevel from side to side; a first length-adjustable member operativelyconnected to said first frame arm and said third frame arm; selectivemovement of said first length-adjustable member causing said distal endof said first frame arm to move up or down; a second length-adjustablemember operatively connected to said second frame arm and said fourthframe arm; selective movement of said second length-adjustable membercausing said distal end of said second frame arm to move up or down; anda level detector for producing and applying leveling signals to each ofsaid length-adjustable members; said leveling signals causing each ofsaid length-adjustable members to position each said first and secondframe arms such that said elongated main frame is maintained in arelatively level orientation when said vehicle encounters uneventerrain.
 2. The rough terrain vehicle as defined in claim 1 wherein saidfirst length-adjustable member is operatively connected to said mainframe and said first frame arm and said second length-adjustable memberis operatively connected to said main frame and said second frame arm.3. The rough terrain vehicle as defined in claim 1 further comprising: afirst pivot axle for connecting said proximal ends of said first andsaid second frame arms, said first pivot axle permitting relativemovement of said first and said second frame arms about said first pivotaxle; and a second pivot axle for connecting said proximal ends of saidthird and said fourth frame arms, said first pivot axle permittingrelative movement of said third and said fourth frame arms about saidsecond pivot axle.
 4. The rough terrain vehicle as defined in claim 1wherein said proximal ends of said first and third arms are adjacent toeach other and said proximal ends of said second and fourth arms areadjacent to each other.
 5. The rough terrain vehicle of claim 1 whereinsaid elongated main frame further comprises first and second suspensionsystems mounted between said main frame and said first and second crossmember.
 6. The rough terrain vehicle of claim 1 wherein each frame armfurther includes a stabilizer arm interconnecting said main frame andeach said arm for providing lateral stability of said distal end to eachsaid frame arm.
 7. The rough terrain vehicle of claim 6 wherein eachstabilizer arm includes a link and is extendable and retractable so thatthe main frame is adjustable relative to the position of the frame arm.8. The rough terrain vehicle of claim 6 wherein each stabilizer arm isof sufficiently wide to provide lateral stability of said distal end toeach said frame arm.
 9. The rough terrain vehicle of claim 6 whereinsaid stabilizer arms interconnecting same main frame and each of saidthird frame arm and said fourth frame arm connected to a tandem arm. 10.The rough terrain vehicle of claim 1 wherein each said third and fourtharm distal ends further comprises a tandem arm operatively connected tosaid frame arm distal end with a tandem arm pivot axle, and said tandemarm is pivotable about said tandem arm pivot axle and having rotatablewheels mounted thereto.
 11. The rough terrain vehicle of claim 10wherein each of said tandem arms is operatively connected to said framearms using a pin and a frame extension with an aperture and a tabinserted through said aperture.
 12. The rough terrain vehicle of claim 1wherein each of said length-adjustable members comprise a hydrauliccylinder having an extendable and retractable piston rod and one of eachcylinder and rod is connected to the third and fourth arms.
 13. Therough terrain vehicle of claim 1 wherein said level detector furtherincludes: a pendulum connected to the top portion of said support bar; atranslation member operatively connected to said pendulum fortranslating lateral movement of said pendulum into corresponding actionto level said vehicle; and a control box to send signals to saidlength-adjustable member for controlling movement of said wheelassemblies.
 14. The rough terrain vehicle as defined in claim 1 furthercomprising a drive train including: a first shaft for receiving powerfrom a differential; and a second shaft for receiving power from saidfirst shaft and for transferring power to a gear box operativelyassociated with the wheels mounted on said first and secondforwardly-extending frame arms; and
 15. The rough terrain vehicle asdefined in claim 14 further comprising a third shaft for receiving powerfrom said second shaft and for transferring power to a gear boxoperatively associated with the wheels mounted on said third and fourthrearwardly-extending frame arms.
 16. The rough terrain vehicle of claim14 wherein said second shaft and said third shaft are each separableinto a right shaft and a left shaft wherein each right shaft and eachleft shaft transfers power independently.
 17. A suspension system for arough terrain vehicle comprising: a v-shaped elongated main frame; firstand second forwardly-extending frame arms located on opposite sides ofsaid main frame, each of which includes a proximal end and a distal end,each said proximal end being pivotably connected to said main frame, andeach said distal end having at least one rotatable wheel mountedthereon; third and fourth rearwardly-extending frame arms located onopposite sides of said main frame, each of which includes a proximal endand a distal end, each said distal end having at least one rotatablewheel mounted thereon; a first generally U-shaped cross member pivotablyconnected to said first and second frame arms and said main frame forsupporting a forward end of said main frame; a second generally U-shapedcross-member pivotably connected to said third and fourth frame arms andsaid main frame for supporting a rearward end of said main frame; saidcross members being configured to enable said main frame and said framearms to pivot about a lengthwise axis of said main frame for the purposeof maintaining said main frame level from side to side; a firstlength-adjustable member operatively connected to said first frame armand a first airbag on said main frame; selective movement of said firstlength-adjustable member causing said distal end of said first frame armto move up or down; a second length-adjustable member operativelyconnected to said second frame arm and a second airbag on said mainframe; selective movement of said second length-adjustable membercausing said distal end of said second frame arm to move up or down; afirst pivot axle for connecting said proximal ends of said first andsaid second frame arms, said first pivot axle permitting relativemovement of said first and said second frame arms about said first pivotaxle; a second pivot axle for connecting said proximal ends of saidthird and said fourth frame arms, said first pivot axle permittingrelative movement of said third and said fourth frame arms about saidfirst pivot axle; and a level detector for producing and applyingleveling signals to each of said length-adjustable members; saidleveling signals causing each of said length-adjustable members toposition each said first and second frame arms such that said elongatedmain frame is maintained in a relatively level orientation when saidvehicle encounters uneven terrain.
 18. The suspension system of claim 17wherein said first airbag is positioned on said third frame arm and saidsecond airbag is positioned on said fourth frame arm.
 19. The suspensionsystem of claim 18 wherein: said first length adjustable member isoperatively connected to a first fixed post located on said first framearm and a first pivot post located on said third frame arm; said firstairbag is operatively connected to said first pivot post and a thirdfixed post on said third frame arm, selective movement of said firstpivot post compresses and expands said first airbag to absorb roughterrain shocks and maintain body control while the vehicle travels overrough terrain; said second length adjustable member is operativelyconnected to a second fixed post located on said second frame arm and asecond pivot post located on said fourth frame arm; and said secondairbag is operatively connected to said second pivot post and a fourthfixed post located on said fourth frame arm, selective movement of saidsecond pivot post compresses and expands said second airbag to absorbrough terrain shocks and maintain body control while the vehicle travelsover rough terrain.
 20. A trailer for traveling over rough terrain andattached to a vehicle that includes a motor for pulling said trailer,said trailer comprising: an elongated main frame for supporting atrailer body; a plurality of rearwardly-extending frame arms located onopposite sides of said main frame, each of which includes a proximal endand a distal end; each said proximal end being pivotably connected tosaid main frame and each said distal end having at least one rotatablewheel mounted thereon; a generally U-shaped cross member associated withsaid plurality of frame arms for supporting said main frame, saidcross-member being pivotably connected to said plurality of frame armsand being configured to enable said main frame and said plurality offrame arms to pivot about a lengthwise axis of said main frame for thepurpose of maintaining said main frame level from side to side; a pivotaxle associated with said plurality of frame arms for connecting saidproximal ends of each said plurality of frame arms, said pivot axlepermitting relative movement of said plurality of frame arms about saidpivot axle; at least one length-adjustable member operatively connectedto said main frame and at least one of said plurality of frame arms;selective movement of said length-adjustable member causing said distalend of at least one of said plurality of frame arms to move up or down;and a level detector for producing and applying leveling signals to eachof said length-adjustable members; said leveling signals causing each ofsaid length-adjustable members to position each said first and secondframe arms such that said elongated main frame is maintained in arelatively level orientation when said vehicle encounters uneventerrain.
 21. The trailer of claim 17 further comprising a plurality offorwardly-extending frame arms located on opposite sides of said mainframe, each of which includes a proximal end and a distal end, each saidproximal end being pivotably connected to said main frame and each saiddistal end having at least one rotatable wheel mounted thereon.
 22. Thetrailer of claim 17 where in said level detector is located on thevehicle.